ᐅ Room smells like marijuana or hashish

Good evening,
We have the following problem: sometimes there is a smell of marijuana or hashish in the children's room. We recently bought the house. It is a prefabricated house with a solid basement. The children's room was completely renovated, meaning new flooring, new wallpaper, and a dropped ceiling installed. This smell does not occur all the time. We cut some holes in the wall to check whether the mineral wool insulation was okay, which it is. The insulation is dry and does not smell like that. We also found no animals or anything else. Please help, as we are getting desperate. Oh, and no one in our household or the neighborhood smokes marijuana.

Attention, a serious, non-sarcastic question.
Are you sure? If the child is around 10-13 years old, they can manage quite a lot. My father only realized it after some time. Children are inventive.

Our child is 18 months old. There is definitely no smoking.

Where do you actually know the smell from?

I know him because I know someone who does that kind of work. I don’t understand how this is related to my question. Whether it is marijuana or hashish, I don’t know because I’m not familiar with it.

Please be more specific! Single-family house? Only the ground floor, only the upper floor, or alternating? Have you checked the flooring? It’s difficult without more information! In the end, there is an authority for that, and their vehicles have blue lights.